In the Django admin interface, is there a way to duplicate an item?

You can save as by just enabling adding this to your ModelAdmin:

save_as = True

This replaces the "Save and add another" button with a "Save as" button. "Save as" means the object will be saved as a new object (with a new ID), rather than the old object.

There's a better (but not built-in) solution here:

https://github.com/RealGeeks/django-modelclone

From their README:

Django Admin has a save_as feature that adds a new button to your Change page to save a new instance of that object.

I don't like the way this feature works because you will save an identical copy of the original object (if you don't get validation errors) as soon as you click that link, and if you forget to make the small changes that you wanted in the new object you will end up with a duplicate of the existing object.

On the other hand, django-modelclone offers an intermediate view, that basically pre-fills the form for you. So you can modify and then save a new instance. Or just go away without side effects.